Computer output printers either use engraved type elements or they produce each character from a series of dots. In printers which produce each character from a series of dots, condensed print can easily be accommodated by merely controlling the mechanism which prints the dots so that the resulting characters have the desired spacing and shape. One can therefore electronically switch from standard pitch printing to condensed pitch printing. With engraved type printers, one generally must mechanically change print elements to change from standard to condensed print. In some engraved type printers such as with band printers, the task of providing condensed print is more difficult.
In particular with the known band printers such as those marketed by International Business Machines Corporation under the type number designation 3262, 4245 and 4248 (or for example see IBM Technical Disclosure Bulletin, June 1978, Vol. 21 No. 1 page 101) one cannot do condensed print because the print hammers are physically spaced for standard pitch printing. If one tried to use a band in these printers which had condensed print characters engraved thereon, some of the print positions would fall between print hammers. Naturally one could build a printer with hammers that are positioned for condensed print, but such a printer would then not be able to efficiently print standard pitch characters.
Printers are known which have double wide print hammers. With an appropriate print band and appropriate control circuitry such printers can print condensed print and with a different print band and appropriate control circuitry such printers can print standard pitch characters. For example, see IBM Technical Disclosure Bulletin, Sept. 1974, Vol. 17 No. 4 page 1012. Another technique for printing condensed print characters is shown in U.S. Pat. No. 4,055,117 (Munday). These and other prior art techniques for printing condensed characters on a printer that can also print standard pitch characters suffer degraded throughput. In printers with double wide hammers throughput is degraded because the pitch of the characters on the band must of necessity be greater than the width of the hammers with the result that it takes longer for a complete character array to pass in front of each hammer. Furthermore, such printers require additional hammer settle out time before adjacent characters can be printed, thereby further degrading the performance. In printers such as that shown in U.S. Pat. No. 4,055,117 (Munday) additional cycles of the print band are required thereby degrading performance.
The prior art therefore shows band printers which have single width print hammers and band printers which have double width print hammers. There is no prior art which shows print hammers which combine a single wide section for printing standard pitch characters and double wide section for printing condensed pitch characters.